Scientists in Indonesia are preparing to auction tens of thousands of artefacts salvaged from a sunken ship off the coast of Java.

The items, which are believed to be more than 1,000 years old, include ceramics, tombstones and swords.

The ancient treasure, which was discovered 18 months ago, is expected to fetch several million US dollars.

About 150,000 pieces are still intact and some of them are expected to go to Indonesia's museums.

Salvaged after 1,000 years at the bottom of the sea, the haul includes bowls from China, Thailand and Vietnam; perfume bottles from Persia; and swords and tablets engraved with Koranic inscriptions.

It is an extraordinary finding because on the ship we can find artefacts that come from five Chinese dynasties

Expert, Syahrowi Nusir

They were only discovered when fishermen off the coast of Java brought up nets clogged with shards of ancient ceramics.

According to Horst Liebner, an expert involved in cataloguing the find, the artefacts probably came from onboard an Indonesian trading ship.

"There is a chance of about 70% that the cargo was loaded in China and then traded down the coast of Palembang and then was heading for Java.

"It's a very funny ship. It's very broad, it's very flat on the bottom, it's very sharp in the bow. It must have been very high if you see the amount of cargo which was on there - about four metres high, maybe four-and-a-half," he said.

'Rewriting history'

According to Indonesia's committee on sunken treasure, the 150,000 pieces could fetch between two and 10 million US dollars if sold off individually.

Several other wrecks in Indonesia have been pilfered by thieves

But the committee is hoping that a museum will buy the collection as a whole. According to committee secretary Syahrowi Nusir, that would increase its value about 10-fold due to is its historical value as a picture of Indonesia 1,000 years ago.

"It is an extraordinary finding because on the ship we can find artefacts that come from five Chinese dynasties. And also we can find another artefact that indicates there was a spread of Islam in Indonesia from the 10th Century.

Indonesia has had problems in the past verifying its ancient artefacts. Several wrecks off its vast coastline have been pilfered by thieves and the artefacts sold off illegally.

In order to avoid the problem this time, the country is rolling out a new system of authentication - certificates for each and every one of the items going on sale.

With tens of thousands of pieces to certify, the auction date could be some way off yet.